fix: workaround for PCAP_SET_RFMON issue (fixes #819, https://github.com/the-tcpdump-group/libpcap/issues/1041, https://github.com/the-tcpdump-group/libpcap/issues/1033)

modules/wifi/wifi.go

@@ -21,7 +21,6 @@ import (
 	"github.com/evilsocket/islazy/fs"
 	"github.com/evilsocket/islazy/ops"
 	"github.com/evilsocket/islazy/str"
-	"github.com/evilsocket/islazy/tui"
 )
 
 type WiFiModule struct {
@@ -581,9 +580,12 @@ func (mod *WiFiModule) Configure() error {
 				// second fatal error, just bail
 				return fmt.Errorf("error while activating handle: %s", err)
 			} else {
-				// first fatal error, try again without setting the interface in monitor mode
-				mod.Warning("error while activating handle: %s, %s", err, tui.Bold("interface might already be monitoring. retrying!"))
-				opts.Monitor = false
+				// first fatal error, forcing monitor mode 
+				// https://github.com/bettercap/bettercap/issues/819
+				opts.Monitor = false;
+				if err := network.ForceMonitorMode(ifName); err != nil {
+					return err
+				}
 			}
 		}
 	}

network/net_darwin.go

@@ -21,6 +21,10 @@ func getInterfaceName(iface net.Interface) string {
 	return iface.Name
 }
 
+func ForceMonitorMode(iface string) error {
+	return nil
+}
+
 func SetInterfaceChannel(iface string, channel int) error {
 	cIface := C.CString(iface)
 	defer C.free(unsafe.Pointer(cIface))

network/net_linux.go

@@ -16,6 +16,22 @@ func getInterfaceName(iface net.Interface) string {
 	return iface.Name
 }
 
+// See https://github.com/bettercap/bettercap/issues/819
+func ForceMonitorMode(iface string) error {
+	_, _ = core.Exec("ip", []string{"link", "set", iface, "down"})
+
+	out, err := core.Exec("iw", []string{"dev", iface, "set", "type", "monitor"})
+	if err != nil {
+		return fmt.Errorf("iw: out=%s err=%s", out, err)
+	} else if out != "" {
+		return fmt.Errorf("Unexpected output while setting interface %s into monitor mode: %s", iface, out)
+	}
+
+	_, _ = core.Exec("ip", []string{"link", "set", iface, "up"})
+
+	return nil
+}
+
 func SetInterfaceChannel(iface string, channel int) error {
 	curr := GetInterfaceChannel(iface)
 	// the interface is already on this channel

network/net_windows.go

@@ -53,3 +53,7 @@ func GetSupportedFrequencies(iface string) ([]int, error) {
 	freqs := make([]int, 0)
 	return freqs, fmt.Errorf("Windows does not support WiFi channel hopping.")
 }
+
+func ForceMonitorMode(iface string) error {
+	return nil
+}